Two-pole circuit breakers have two electrical branches or poles through which electrical power is provided to one or more loads. Residential two-pole circuit breakers in the U.S., for example, typically provide 240 volts instead of 120 volts to devices and/or appliances such as electric dryers, water heaters, well pumps, and/or electric ranges. When an electrical fault is sensed in one pole, the two-pole breaker typically “trips” both poles (i.e., interrupts power through both poles). This is often referred to as a common trip, which helps to prevent electrical shock hazards and/or equipment damage when a hazardous electrical condition is sensed by the breaker.
Two-pole circuit breakers usually have an internal rotating trip bar that causes the second pole to trip in response to the first pole tripping. Trip bars are typically connected to a tripping mechanism in each pole and may require tight design tolerances and precise alignment in order to function properly. Accordingly, trip bars may require careful monitoring and inspection during production and assembly. Tooling may be difficult to maintain with tight design tolerances, and batches of produced trip bars may be subject to rejection for not meeting stringent design specifications. Trip bars may also be subject to surface wear during use that may render the trip bar unable to trip the second pole.
A need therefore exists to provide an improved trip bar in two-pole circuit breakers.